Polymerizable mixture of vinylidene monomer and unsaturated polyester containing a polycarboxylic adduct of hexahalocyclopentadiene and laminate containing same



, heat is of considerable commercial importance.

United States atent i POLYMERIZABLE MIXTURE OF VINYLIDENE MONOMER AND UNSATURATED POLYESTER CONTAINING A POLYCARBOXYLIC ADDUCT OF HEXAHALOCY'CLOPENTADIENE AND LAM- INATE CONTAINING SAME Paul Robitschek, Wilson, and Claude Thomas Bean, Niagara Falls, N. Y., assignors to Hooker Chemical Corporation, Niagara Falls, N. Y., a corporation of New York No Drawing. Application January 24, 1957 Serial No. 635,948

19 Claims. (Cl. 154-43) This invention relates to new resinous compositions, and to methods for their manufacture, comprising a copolymerizable mixture of an unsaturated polyester (also referred to in the art as an unsaturated alkyd, or, unsaturated linear polyester chain resin) and an unsaturated cross-linking agent, said copolymerizable mixture including a polyhydric alcohol containing aliphatic carbon to carbon unsaturation and a component which imparts flame retardance to the polymerized mixture, which is a chemical reaction adduct of hexahalocyclopentadiene and a polycarboxylic compound containing aliphatic carbon to carbon unsaturation wherein the halogen is selected from the group consisting of chlorine, bromine, fluorine, and mixtures thereof. This invention also relates to the polymerized flame retardant compositions in their finally reacted form, that is, as resinous insoluble, infusible copolymers, and to methods for their preparation.

This application is a continuation-in-part of our copending application Serial Number 308,921, filed September 10, 1952, now United States Patent No. 2,779,701.

The production of infusible, insoluble polyester resins which are flame retardant and have high resistance to For instance, castings, moldings, foamed articles or laminated structures bonded by polyester type resins are for many uses required, or at least desired, to be resistant to fire and are also required to endure heat without deterioration. A typical illustration of an application having such a requirement is had in castings for live electrical contacts which must not be ignited by sparks or be deteriorated by heat generated therein. Structural members, pipes, wall coverings, panels, and ash trays, etc., are further illustrations where flame retardance is desirable.

Heretofore certain chemical adducts have been disclosed as being useful in the preparation of polyester resins; for example, it is known that the maleic acid-cyclopentadiene Diels-Alder adduct resulting from the diene synthesis and its reaction products with alpha, betaunsaturated dicarboxylic acids or 'anhydrides and glycols form resinous compositions which may be made insoluble and infusible by further reaction with copolymerizable oleiins to form a cross-linked copolymer. Such compositions are chemically diiierent from the products of this invention because the double bond remaining in the linear unsaturated polyester so produced is highly reactive and can enter directly into the cross-linking reaction, whereas, the corresponding linkage in the halogen-containing derivatives employed in making the compositions of this invention is non-reactive in said copolymerization reaction; moreover, they do notpossess flame retardance. Attempts have been made to impart flame retardance to such hydrocarbon type resinous polyester compositions by incorporating therein inert fireproofing agents, such as antimony oxide or chlorinated parafiin wax, as fillers which do not enter into chemical reaction with the comrepeats of the resin; however, this results in a loss in the the polyesters.

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desirable properties, particularly with respect to heat resistance, which are usually associated with polyester resins, and the property of being able to produce satisfactory articles of commerce may be seriously impaired. Other attempts to impart flame retardance are also known which involve chemically combining tetrachlorophthalic acid or anhydride in the polyester resin. Compositions so produced are chemically unrelated to the products of this invention; they have only poor flame retardant properties and they usually possess low stability and low strength at elevated temperatures; therefore, they are not entirely satisfactory for many applications. Still other attempts involving the use of certain unsaturated organic phosphorus compounds as cross-linking agents which impart flame retardance to the final polyester resin have likewise been found unsatisfactory.

It is an object of this invention to provide resinous compositions which are highly resistant to burning and yet possess many of the desirable characteristics usually associated with polyester resins. A further object is to provide resinous compositions which are highly resistant to exposure at elevated temperatures.

It is a particular object of this invention to provide such polyester resinous compositions which include a polyhydric alcohol containing aliphatic carbon to carbon unsaturation and a component which imparts flame retardance to the polymerized mixture, which is a chemical reaction adduct of hexahalocyclopentadiene and a polycarboxylic compound containing aliphatic carbon to carbon unsaturation wherein the halogen is selected from the group consisting of chlorine, bromine, fluorine, and mixtures thereof.

A still further object is to prepare resinous compositions which are suitable for casting, molding, foaming or laminating and which are characterized by possessing the desirable properties usually required in resins in the preparation of castings, moldings, foamed articles and laminates, and which are also characterized by being capable of being formed into articles of commerce which have a pleasing appearance and Wide utility. A particular object of this invention is to make available in commerce compositions comprising a mixture of an unsaturated polyester and an olefinic cross-linking agent, with or without the presence of catalyst and/or inhibitors and/or chain terminating agents and/or promoters or accelerators, which are capable of copolymerization to an insoluble, infusible, fire resistant polyester resin. A further object is to provide methods for chemically combining hexahalocyclopentadiene in the form of an adduct into A still further objective is to provide methods for the preparation of these unsaturated polyesters and their combination with olefinic cross-linking agents. These objects, and still others which will become apparent to those skilled in the art on consideration of our specification and claims, are accomplished by the present invention.

In accordance with this invention the unsaturated polyester may contain the component which imparts flame retardance in either the polycarboxylic acid or anhydride unit. The unsaturated polyester must contain unsaturation which is capable of copolymerization with the unsaturation in the cross-linking agent. Such copolymerizable unsaturation is an essential characteristic of the unsaturated polyester portion of the mixture of this invention. We have found that the double bond, remaining in-a polyester chain, which is derived from the reaction adducts of hexahalocyclopentadienes with monoolefinic polycarboxylic acids or anhydrides, including acid chlorides is not sufliciently reactive to enter into the crosslinking reaction. We render such polyesters copolyrnerizable in the cross-linking reaction by incorporating in the esteritication product a reactive and unsaturated 0 chemical ingredient which retains its active unsaturation after being chemically combined in the polyester chain. iltcrnatively, or in addition to including flame retardant components in the unsaturated polyester, as just described, and in accordance with this invention, the cross-linking agent may contain the component which imparts flame rctardance to the polyester resins of this invention.

in our copending application Serial Number 308,921. filed September 10, 1952, now United States Patent 2,779,701, we have disclosed the use of an unsaturated polyhydrie alcohol as the source for both the alcohol groups which are necessary in the polyesterification reaction and as the source for the double or triple bonds which are necessary in the cross-linking or polymerization reaction. In the instant application, as the following examples and claims show, we particularly illustrate and claim this aspect of our invention.

The reactant components of this invention which im' part flame retardance to the final polymerized resinous compositions by their incorporation in either the linear polyester or the unsaturated cross-linking agent may be prepared by effecting the chemical addition of a hexahalocyclopcntadicne with an unsaturated polycarboxylic acid or acid anhydride or acid halide, in a manner as shown in tr e following equation in which the specific reactants are given for purposes of illustration only:

This and similar Diels-Alder type reaction adducts of heiiahalocyclopcntadienes which are more fully disclosed hereinafter, can be esterified with a polyhydric alcohol to produce a soluble polyester chain containing the olefinic linlrage originally present in the Diels-Alder adduct, as exemplified by the following product formed by esterification of the product of reaction (I) with ethylene However the olefinic linkage contained in such chlorine containing polyester chains II has been found by us to he unreactive in the copolymerization reaction with olefin c cross-linking agents, such as vinyl acetate, styrene, divinyl compounds, diallyl compounds, etc., even in the presence of the most active catalysts for such reactions.

Jr e have found that in order to render such polyesters, ll. containing such Diels-Alder adducts of hexahalocyclopentadienes. copolymcrizable with olefinic cross-linking agents, whereby infusible, insoluble, and flame retardant eopolymers may be produced. it is necessary to introduce copolymerizable unsaturation into the polyester chain. This may be accomplished by adding to the polyester ll, maleic anhydride, which is a particularly suitable material for this use; however any unsaturated polycarboxylic acid or nnhydride. or, polyhydric alcohol, or esters thereof, including the acid chlorides, capable of esterification without losing its ability to copolymerize with olefinic cross-linking agents may be employed. Alternatively, or in addition to providing unsaturation in this manner, we may also provide for it by employing a Diels- Alder reactant with hexahaloeyclopentadiene which has more than mono-olcfinic unsaturation, for example, a diolefin or an acetylenic compound, and which retains, after being esterified in the polyester chain, an unsaturated linkage reactive in the cross-linking reaction.

However, rather than first reacting the acid adduct of reaction 1' with a material such as ethylene glycol, having no alipnntic carbon to carbon unsaturation, as was done when preparing the polyester II and then adding a material such as maleic anhydride to this in Order to Obtain copolymerizable unsaturation, we may directly obtain a polyester having copolymerizable unsaturation by reacting the acid adduct of reaction I with a polyhydric alcohol containing aliphatic carbon to carbon unsaturation. Among such polyhydric alcohols containing aliphatic carbon to carbon unsaturation which may be used for this purpose are Z-butene-lA-diol, alpha-ally] glycerol ether and butynediol.

The resinous copolymers of this invention may also be prepared by first effecting the esterification of the selected polycarboxylic acids with the desired polyhydric alcohols in the presence of the reactive unsaturated chemical in grcdient, whereby an unsaturated polyester is formed; then mixing the resulting composition with the chosen copolymerizable olefinic cross-linking agent; and, thereafter copolymerizing the mixture to form an insoluble, infusible polyester resin. Another method which may be employed for producing resinous copolymcrs of this invcntion which is in accordance with our findings comprises effecting the chemical addition of hexahalocyclopenta diene to less than the total theoretical number of olefinic linkages contained in an unsaturated polyester molecule. For example, by effecting the Diels-Aldcr reaction of one molecule of hexahalocyclopentadiene with more than one molecule of ethylene glycol maleate, a product is pro duced which contains the hexahalocyclopentadiene in chemical combination in the polyester chain and which also contains active unsaturation which is copolymerizable with the cross-linking agent and thereafter copolymerized in a manner similar to that described. Estcrification of the desired ingredient may be effected in the presence of esterification catalysts and/or chain terminating agents. A preferred procedure involves introducing the selected ingredients to be esterified, in predetermined proportions, into a suitable esterification vessel provided with heating and/or cooling means, an agitator, means for maintaining an atmosphere of an inert gas such as nitrogen or carbon dioxide over the reaction mixture, means for removing water of esterification, an inlet, an outlet, and any other accessories necessary for the reaction. The charged reactants are blanketed with an inert atmosphere, then agitated and heated to effect the reaction for the specified period of time. After the desired degree of re action has been attained, as conveniently determined by employing the acid number technique or measuring the amount of water liberated, the reaction mixture is cooled. The resulting product, if solid, and if prepared in accordance with the first procedure described, is broken up and then mixed with the olefinic cross-linking agent at room temperatures, preferably in the presence of a polymeriza tion inhibitor. If prepared in accordance with the second method, a hexahalocyclopentadienc is chemically added to a soluble unsaturated polyester molecule in an amount insufficient to react out all the double bonds in the polyester and the material resulting by this treatment is then compounded with the olefinic cross-linking agent.

We have found that the cross-linking agent may be advantageously combined with unsaturated polyesters prepared in accordance with these methods while the unsaturated polyester is at an elevated temperature and that the olefinic cross-linking agent may also be at an elevated temperature thereby facilitating solution and mixing. To prevent premature polymerization at this stage, a polymerization inhibitor is advantageously added to the mixture, or preferably to one of its components prior to mix ing, especially if the mixture is to be stored or shipped in commerce prior to curing or effecting the copolymeri' zation reaction into the insoluble, infusible polyester resin. Alternatively, or in addition to including a polymerization inhibitor, a catalyst and/or promoter for the copolymerization may be added, particularly if it is de sired to make available in commerce a composition which is ready for polymerization and does not require further chemical additions in order to be used, as is commonly known in the art. I

In order that this invention may be'more' readilyunderstood and to further illustrate the details thereof, the following examples are given which show preferred compositions of this invention and methods for their preparation. cyclopentadienes disclosed herein are new compositions of matter.

In the following examples, in which parts are given by weight unless otherwise stated, the common properties of the resins were determined by the generally accepted procedures known in the art.

Example 1 Fifty-two and eight-tenths parts of ethylene glycol and 90 parts of diethylene glycol were charged into an esterification or resin vessel provided with heating and/ or cooling means, an agitator, means for maintaining an atmosphere of an inert gas over the reaction mixture, means for removing water of esterification, temperature recording means, charging inlets and outlets, etc. The charge was blanketed with an inert atmosphere of nitrogen, agitated, heated to a temperature between about 80 and 100 degrees centigrade, then 394.7 parts of 1,4,5,6,7,7-hexachlorobicyclo-(2.2.l) 5 heptene-2,3-dicarboxylic anhydride (hereinafter referred to as HET), prepared by the method which involves the Diels-Alder reaction of hexachlorocyclopentadiene with maleic anhydride, was blended into the agitated glycols. Seventy and eight-tenths parts of maleic anhydride was then blended into the charged reactants while the reaction mixture was being raised to a temperature of about 160 to 170 degrees centigrade by application of external heat. The water of esterification liberated during the reaction was separated and periodically measured and the acid number of the reaction mixture was also periodically measured to determine the progress of the reaction. When an acid number of approximately 55 was approached, 3.6 parts of tetrahydrofurfuryl alcohol was added to the reaction mixture. Upon reaching an acid number of about 45, the entire contents of the reaction vessel was cooled, then cast into pans under an inert atmosphere. A transparent, faintly colored, hard, brittle, soluble material having 38.4 percent by weight chlorine content, which melts in a temperature range above room temperature and below 100 degrees centigrade and has a specific gravity at room temperature of about 1.45 was obtained.

Example 2 One hundred grams of the cast product recovered in Example 1 was broken into small lumps, then added in small portions, with agitation, to- 30 grams of styrene maintained under an inert atmosphere, containing 0.03 gram of hydroquinone, until completely dissolved. Complete solution consumed a period of more than 24 hours even with continued vigorous agitation. The resulting mixture was a clear, substantially colorless solution having a viscosity of about 30 poises at 25 degrees centigrade on a Gardner bubble viscometer.

Example 3 Fifty parts of the mixture prepared in Example 2 were agitated with 0.5 part of a catalyst mixture comprising 50 parts of benzoyl peroxide and 50 parts of tricresyl phosphate. The resulting mixture was cast in millimeter diameter glass tube and set by heating at a temperature of about 80 degrees centigrade for a period of about one half hour. A hard, tough, clear, insoluble, infusible, substantially colorless polyester resin was obtained which has a 30 percent chlorine content by weight and is immediately self-extinguishing on removal from an oxidizing flame.

Example 4 Nine hundred thirty three and one tenth (933.1) parts Certain of the Diels-Alder adducts of h'exahalo-' of HET was placed in a tri-n'ecked one liter flask. To this was added 221.7 parts of 2-butene-1,4-diol. The flask was fitted with a nitrogen bubbler, a mercury sealed stirrer and a Y tube. The Y tube was fitted with a thermometer extending into the resin and a vertical condenser with only air in the jacket. The condenser was approximately 15 inches long and the top of this condenser was connected to another condenser set for distillation and collection of the distillate in a receiver. The reaction flask was lowered into an oil bath and the temperature of the mixture raised to 160 degrees centigrade. This mixture was stirred and nitrogen was slowly bubbled through it. After approximately 22 hours and when the acid number of the resin was found to be 84, the resulting resin was poured into a tray. This resin was light brown in color, had a chlorine content of 45.0 percent by weight and was solid at room temperature.

Example 5 To 100 par-ts of the resin of Example 4 was added 40 parts of vinyl acetate monomer and to 50 parts of this mixture was added 1 gram of a catalyst mixture comprising 50 parts of benzoyl peroxide and 50 parts of tricresyl phosphate. The resulting mixture was poured into a test tube which was placed in a constant temperature water bath. The mix slowly gelled to a hard, clear, casting having a chlorine content of 32.0 percent by weight and which was insoluble and infusible. A small piece of this casting when placed in a strongly oxidizing flame extinguished itself immediately when removed from the flame.

Example 6 Examples 4 and 5 were repeated except that 978.4 parts of l,4,5,6,7,7-hexachlorobicyclo-(2.2.1)-5-heptene- 2,3-dicarboxylic acid (hereinafter referred to as HET acid) were substituted for the 933.1 parts of HET. This Example 7 Six hundred sixty and eight tenths parts of alpha allyl glycerol ether were charged into a resin making vessel provided with heating and/ or cooling means, an agitator, means for maintaining an atmosphere of inorganic gas passing through the reaction mixture, means for removing water of esterification, temperature recording means, charging inlets and outlets, etc. The charge was blanketed with an inert atmosphere of nitrogen, agitated, heated to a temperature of to degrees centigrade then 1945 parts of HET acid were blended into the diol. The temperature of the reaction mixture was raised to 160 degrees centigrade and maintained there for a period of 16 hours. At the end of this time an acid number of 16 had been reached. The resulting resin was poured into a tray and allowed to cool at room temperature. This resin was light brown in color and a solid at room temperature and had a chlorine content of 43.6 percent by weight. To parts of this base resin was added this mixture was added 1 gram of a catalyst mixture comprising 50 parts of benzoyl peroxide, and 50 parts of tricresyl phosphate. The resulting mixture was poured into a test tube which was placed in a constant temperature Water bath. The mix slowly gelled to a hard, clear casting having a chlorine content of 31.0 percent by weight and which was insoluble and infusible. A small piece of this casting when placed in a strongly oxidizing flame extinguished itself immediately when removed from the flame.

Example 8 Example 7 was repeated except that 1855 parts of HET were substituted for the 1945 parts of HET acid. This gave a resin having 43.6 percent by weight of chlorine before the vinyl acetate was added and 31.0 percent by weight after the vinyl acetate was added. A casting of the resinous composition after having been polymerized with vinyl acetate was a hard thermoset product which extinguished itself immediately when removed from a strongly oxidizing flame.

Example 9 Eight and six tenths parts of butyne diol were charged into a resin making vessel provided with heating and/or cooling means, an agitator, means for maintaining an atmosphere of inorganic gas passing through the reaction mixture, means for removing water of esterification, tem' perature recording means, charging inlets and outlets, etc. The charge was blanketed with an inert atmosphere of nitrogen, agitated, heated to a temperature of 80 to 90 degrees centigrade then 38.9 parts of HET acid were blended with the butyne diol. The temperature of the reaction mixture was raised to approximately 160 degrees centigrade and maintained there for about 16 hours or t until an acid number of was reached. The resulting resin was poured into a tray and allowed to cool at room temperature. This resin was a hard, brittle. thermoplastic polymer containing 45 percent chlorine. To this resin was added 18.3 parts of styrene and this mixture was then copolymerized using suitable amounts of benzoyl peroxide as a catalyst. The resultant copolymer was a hard. tough, thermoset solid containing 32 percent chlorine that was immediately self-extinguishing on removal from a strongly oxidizing flame.

Example l0 Eight and six tenths parts of butyne diol were charged into a resin making vessel provided with heating and/or cooling means, an agitator, means for maintaining an atmosphere of inorganic gas passing through the reaction mixture, means for removing water of esterification, temperature recording means, charging inlets and outlets. etc. The charge was blanketed with an inert atmosphere of nitrogen, agitated, heated to a temperature of 80 to 90 degrees Centigrade, then 37.1 parts of HET anhydridc were blended with the butyne diol. The temperature of the reaction mixture was raised to approximately 160 degrees centigrade and maintained there for about 16 hour-t or until an acid number of was reached. The resulting resin was poured into a tray and allowed to cool at room temperature. This resin was a hard, brittle. thermoplastic polymer containing 45 percent chlorine. To this resin was added 18.3 parts of styrene and this mixture was then copolymerized using suitable amounts of benzoyl peroxide as a catalyst. The resultant copolymer was a hard, tough, thermoset solid containing 32 percent chlorine that was immediately self-extinguishing on removal from a strongly oxidizing flame.

Example 11 Eight and six tenths parts of butyne diol were charged into a resin making vessel provided with heating and/or cooling means, an agitator, means for maintaining an atmosphere of inert gas passing through the reaction mixture, means for removing water of esterification, temper ature recording means, charging inlets and outlets, etc. The charge was blanketed with an inert atmosphere or nitrogen, agitated, heated to a temperature of to degrees Centigrade, then 37.1 parts of HET anhydride were blended with the butyne diol. The temperature of the reaction mixture was raised to approximately 160 degrees centigrade and maintained there for about 16 hours or until an acid number of 65 was reached. The resulting resin was poured into a tray and allowed to cool at room temperature. This resin was a hard, brittle, thermoplastic polymer containing 45 percent chlorine. To this resin was added 18.3 parts of acrylonitrile and this mixture was then copolymerized using suitable amounts of benzoyl peroxide as a catalyst. The resultant copolymer was a hard, tough, thermoset solid containing 32 percent chlorine that was immediately self-extinguishing on removal from a strongly oxidizing flame.

The following example illustrates the typical properties of copolymer compositions of the nature of this invention obtained by casting in the manner which has already been described.

Example 12 A polymerizable mixture of unsaturated polyester and styrene prepared in a manner after Examples 1 and 2 possessed the following physical properties:

Viscosity at 25 C Approximately 27 poises.

C0101 Below as defined by the American Public Association standards.

Odor Styrene.

Clarity Transparent. Specific gravity at 23 C 1.36.

i lefractive index at 21.5 C 1.5517.

Polyester concentration 77 percent. Percent chlorine 30 percent.

Acid number Approximately 35.

The resin was found to have only a 4.9 percent shrinkage in volume when fully cured in the presence of one percent by weight of benzoyl peroxide at 80 degrees Centigrade for about one-half hour. The cured polyester resin is a hard, tough, transparent material having a specific gravity of 1.43 and an ASTM D 757-49 burning rate of 0.26 inch per minute immediately after it was prepared. After being heat aged for three days at 200 degrees centigrade it had a burning rate of 0.16 inch per minute and after two weeks of heat aging at 200 degrees centigrade it had a burning rate of 0.14 inch per minute. This was an entirely unexpected but desirable property because with time and use the resin acquires more flame retardance, rather than losing it, as is commonly encountered with other polyester resins in the art. Al' though the resin has a thirty percent chlorine content, there have been no indications of toxicity which are commonly encountered with chlorinated compounds. The polyester resin does not cause dermititis on handling by humans. Examination of the fumes evolved by exposing the cured resin to temperatures as high as 350 degrees Centigrade do not indicate the presence of any objectionable toxic chlorinated materials, which is indeed an unusual property to be associated with highly chlorinated materials. The electrical properties of the resin were found to be as follows:

Frequency Dielectric Dissipation Constant lacf r The following example illustrates a molding formulation containing a composition of this invention and the molded product resulting therefrom.

Example 13 A molding formulation was compounded by mixing 80 grams of styrenatcd resin prepared after the manner of Example 2 with 1.6 grams of a mixture of 50 parts of benzoyl peroxide and 50 parts of tricresyl phosphate and intermittently blending into the solution, 60 grams of glass fiber cut into two inch length. This material was placed in a two inch diameter mold then subjected to a temperature of degrees centigrade and a pressure of thick was obtained. The molding W'as self-extinguishing.

on removal from an oxidizing flame, shock resistant even when dropped from a two-story building on a concrete pavement and had a pleasing appearance.

The processing techniques and the chemical reactions depicted herein for producing the necessary ingredients to be used in making the compositions of this invention are subject to various modifications and the proportions of ingredients may also be varied without departing from our invention.

The temperature for carrying out the reaction between the polyhydric alcohols and polybasic acids or between the acid adducts and the polyhydric alcohols ranges from 100 degrees centigrade to 200 degrees centigrade, although higher or lower temperatures can be used; preferably temperatures around 150 degrees centigrade to 180 degrees ccntigrade are advantageously employed.

An inert gas such as nitrogen is passed through the mixture in a preferred procedure to accelerate the progress of the reaction and allow for good color of the product. The progress of the reaction is followed by measuring the rate of water liberated, by the viscosity of the resin, by its acid number, or by other methods commonly known in the art. The extent to which the reac tion is carried out will depend on a number of factors, such as the desired viscosity, melting point, duration of reaction, etc.

Esterification catalysts such as para-toluene sulphonic acid, benzene sulphonic acid, beta naphthalene sulphonic acid, etc., or amines such as, pyridine, triethyl amine, quinoline, etc., may be added'to the reaction mixture.

The proportion of polyhydric alcohol is approximately controlled by the total mol proportion of acids in the esterification reaction mixture. In making certain compositions of our invention we prefer to react the polyhydric alcohols and polybasic acids in a roughly equimolar proportion; however, either the acids or alcohols may be in substantial excess, if it is desired to form a low molecular weight polyester resin.

A chain stopper may be added in a minor proportion depending on the molecular weight of the linear unsaturated polyester chain desired, in order to rapidly terminate the growth of the unsaturated polyester chain during the esterification reaction and when the desired acid number is being approached, or, to reduce the number of free carboxyl or hydroxyl groups, or to introduce a hydrocarbon terminal residue. Among the compounds which may be used as chain stoppers during the esterification reaction whereby the unsaturated polyester chain is produced are a wide variety of monohydric alcohols, such as butyl, hexyl, octyl, dodecyl, benzyl, and tetrahydrofurfuryl alcohols, or, monobasic acids such as, acetic, propionic, butyric, ethyl hexoic, and benzoic.

The solution or mixture of unsaturated polyester and olefinic cross-linking agent is preferably made while the unsaturated polyester is still hot, thereby facilitating rapid solution. Alternatively, the unsaturated polyester may be cooled and stored and when ready for mixing may be heated in order to facilitate solution in the olefinic cross-linking agent, which may also be heated. The solution may, of course, be made in the cold, especially if there is any possibility of explosion in handling the hot olefinic cross-linking agent or if polymerization of the olefinic cross-linking agent cannot he prevented when at elevated temperatures even by the presence of inhibitors therefor.

The proportion of ol finic cross-linking agent to unsaturated polyester may be varied within the ultimate limits of each Without departing from the scope of this invention, in order to make the solution or mixtures of this invention which may be set to the infusible, insoluble, polyester resin. For example, only a small proportion of olefinic cross-linking agent is needed when the proportion of reactive cross-linkable olefinic bonds in the unsaturated polyester is very small; and a still smaller proportion of olefinic cross-linking agent may be employed if it is desired to react only a part of the total of said unsaturated bonds in such polyester in the cross-linking reaction. On the other hand, a major proportion of olefinic cross-linking agent to unsaturated polyester may be employed when the proportion of reactive cross-linkable olefinic bonds in the unsaturated polyester is high; and a still higher proportion of olefinic cross-linking agent will be required if it is desired to react a major part of the total of said unsaturated bonds in such polyester in the cross-linking reaction. In general, the concentration of the unsaturated polyester in the olefinic cross-linking agent and unsaturated polyester mixture may vary between about 10 and 90 percent. In certain formulations and in order to accentuate a large number of desirable properties in the polyester resin produced, we find it preferable to employ between about 15 and 45 percent of the olefinic cross-linking agent by weight of the total resin and cross-linking agent, e. g., styrene, when the unsaturated polyester is similar to that produced in Example 1. However, it is to be understood that this preferred concentration is a variable which is dictated by the particular properties of the materials employed and the particular properties desired in the polyester resin produced.

Polymerization inhibitors, usually of the order of 0.001 to 1 percent of the composition may be added to prevent premature polymerization. Among the inhibitors which may advantageously be employed to prevent the premature polymerization of the mixture of unsaturated polyester and olefinic cross-linking agents, particularly if the mixture is to be stored or shipped in commerce prior to curing, are substances such as hydroquinone, benzoquinone, para-tertiary-butyl catechol, para-phenylene diamine, tri-nitrobenzene, and picric acid.

Polymerization catalysts are preferably added to the mixture of unsaturated polyester and olefinic cross-linkin'g agent to effect setting or curing. Catalysts such as benzoyl peroxide, acetyl peroxide, lauroyl peroxide, methyl ethyl ketone peroxide, and cumene hydroperoxide, have been found satisfactory. Such catalysts are used in a proportion of 0.01 to 10 percent depending on the efficiency of their action and whether or not substances which inhibit polymerization are present in the mixture to be cross-linked. The polymerization reaction may also be hastened by effecting it in the presence of promoters such as metals or metal salts, such as cobalt resinate, cobalt maleate, and cobalt naphthenate, or by amines such as dibutyl amines, or mercaptans such as dodecyl mercaptan. These are used in proportions similar or smaller to that stated for catalysts.

The polymerization conditions for effecting the crosslinking reaction between the unsaturated polyesters of this invention and the olefinic cross-linking agent may be selected from a wide variety of techniques but usually involve the application of heat or light. Although pressure is not a required condition for effecting polymerization of the polymerizable mixtures embraced within this invention, thereby providing for a decided advantage over other resin mixtures known heretofore, it is sometimes advantageously employed, particularly when it is desired to make laminates in preformed shape. The pressures found satisfactory for this purpose are relatively low compared to those required for molding or laminating other type resins than involved herein and may be of the order of that obtained by pressing glass plates having a fiber glass mat or laminate impregnated with the polyvester resin sandwiched therebetween.

The temperature at which polymerization is effected depends on a variety of factors, particularly the boiling point of the olefinic cross-linking agent and the exothermic characteristics of the polymerization mixture. A temperature is selected which will give a suitable reaction rate and yet not cause substantial volatilization, and in the 2,sss,794.-

case of producing very thick castings, which will not produce a product which is crazed, cracked, etc.

Various adducts of hexahalocyclopentadienes such as 1,4,5,6,7,7-hexachlorobicyclo-(2.2.l -heptene-2,3-dicarboxylic acid; 1,4,5,6,7,7-hexachlorobicyclo-(2.2.l) 5-heptene-2,3-dicarboxylic anhydride; l,4,5,6,7,7-hexachloro- 2-chlorobicyclo-(2.2.l )-5 heptene 2,3 dicarboxylic anhydride; diallyl l,4,5,6,7,7-hexachlorobicyclo-(2.2.1)-5- heptene-2,3-dicarboxylate; 1,4,5,6,7,7-hexachloro-2-methyl-bicyclo-(2.2.l)-5-heptene-2,3 dicarboxylic anhydride; mono-methyl ester of 1,4,5,6,7,7 -hexachlorobicyclo- (2.2.1)-5-heptene-2,3-dicarboxylic acid; l,4,5,6-tetrachloro 7,7 difiuoro-bicyclo-(2.2.l)-5-heptene-2,3-dicarboxylic acid; l,4,5,6,7,7-hexachlorobicyclo-(2.2.1)-5-heptenc-2-acetic-2-carboxylic anhydride; and the adduct of hexahalocyclopentadiene and fumaric acid may be employed in making compositions embraced Within the scope of this invention. As used herein and in the appended claims the term halo includes the chloro, bromo and iluoro substituted cyclopentadiencs wherein all of the hydrogens are replaced by one or more of the foregoing halogens. While hexachlorocyclopentadiene is today the most readily available commercial hexaholocyclopentadiene, we have found that the mixed perhalo compounds are useful in making Diels-Alder adducts which can be chemically combined into the saturated polyester components of this invention.

in fact, hexaehlorocyclopentadiene in which one or two of the chlorine atoms has been replaced with bromine, appears to afford an even higher degree of fiame retardance in the polyester resins. The polyester resins made from a hexahalocyclopentadiene in which some of the chlorine of hexachlorocyclopentadiene has been replaced with fluorine atoms, are exceedingly interesting materials possessing enhanced heat resistance and aging properties. The foregoing applies Whether the hcxahalocyclopentadiene is utilized as a raw material in the malting of the copolymerizable linear polyester or the unsaturated cross-linking agent.

The hexahalocyclopentadiene radical may be combined into the polycarboxylic acid unit of the unsaturated polyester chain in a variety of ways such as by effecting the Dicls-Alder reaction of the hexahaloeyclopentadiene with unsaturated polycarboxylic acids such as maleic or furnaric; substituted maleics or fumarics such as, citraconic, chloromaleic, mesaconic, and pyrocinchonic; acetylene clicarbosylic acids; and also ethylenic substituted succinic anhydrides or acids, such as, aconitic and itaconic, and

endomethylene tetrahydrophthalic acid or anhydride, etc. 7

instead of employing the polycarboxylic acids or anhydridcs in the Diels-Alder reaction, adducts of hexahalocyclopentadiene with substances which produce an equivalent polyester chain upon reaction with a polyhydric alcohol can he used; for instance, acid chlorides, or. esters of the acids or anhydrides may also be used. A typical illustration is had in the Diels-Alder reaction of hertachlorocyclopentadiene with furnaryl chloride to produce 1,4,5,6,7,7-hexachlorobicyclo-(2.2.l)-5-heptene- 2.3-dicarbonyl chloride followed by the esterification of this with ethylene glycol and maleic anhydride or with polyhydric alcohols containing aliphatic carbon to carbon unsaturation to produce the unsaturated polyester.

Alternatively, or in addition to including the flame rctardant component in the unsaturated polyester, we have found that the chlorine content of the final polyester formulations may be obtained, or substantially increased, by employing a cross-linking agent which also contains the component which imparts flame retardance to the final compositions of this invention. Among such crosslinking agents which may be useful for this purpose are the following: Diallyl l,4,5,6,7,7 hexachlorobicyclo- (2.2. l)-5-heptene 2,3 dicarboxylate; cliallyl-l,4,5,6,7,7- hexachloro Z-rnethylbicyclo-(2.2.1)-5-heptene-2,3-dicarboxylate; diallyl-l,2,4,S,6,7,7-heptachlorobicyclo-(2.2.l)- 5-heptene-2,S-dicarboxylate; and triallyl-1,4,5,6,7,7-hexa- 12 chlorobicyclo-(2.2.l )-5 heptene-Z-acetate-2,3-dicarboxylate. These compounds can be prepared by reacting hcxachlorocyclopentadiene with the indicated dicarboxylic acid and esterifying the resultant product with an unsaturated alcohol such as allyl alcohol. Other cross-linking agents may advantageously be employed; for example, reaction products of hcxachleroeyclopentadiene with isoprene or butadiene retaining a reactive unsaturated linkage can be used as cross-linking agents directly without further reaction. Still other methods for the preparation of the unsaturated cross-linking agents, employing type reactions known to the art, will be apparent from the foregoing. In addition materials such triallyl cyanurate may be employed for improving heat resistance; divinyl benzene, monochlorostyrene, dichlorostyrcne, diallyl phthalate, diallyl maleate and similar monoor polyvinyl or monoor poly-allyl derivatives are also useful.

It is apparent from a consideration of the foregoing examples and the foregoing discussion that the particular chemical ingredients selected and their relative proportions may be varied over a wide range to produce a wide variety of compositions embraced within this invention. It should be emphasized that modifications can be made to accentuate any given property or combination of properties desired. For example, hardness in the final polyester resin can be varied by using short chain polyhydric alcohol and acids or long chain polyhydric alcohols and acids; the viscosity of the mixture comprising the unsaturated polyester and the olefinic cross-linking agent may be varied by changing the ratio of unsaturated polyester to olefinic cross-linking agent; and the curing characteristics of such mixtures can be varied by changing the kind and proportion of polymerization catalyst employed. In order to accentuate both flame retardance and heat resistance, we prefer that the hexahalocyclopcntadicne content should not be less than that sulficient to supply a final product of not less than ten percent of halogen by Weight of the polyester resin composition; the upper limit for the hexahalocyclopentadiene content is generally dictated by practical limits determined by the minimum necessary concentration of glycols and unsaturated dibasic acids not being adducts of hexahalocyclopentadicne and olefinic compounds to give resinous compounds capable of being hardened and this upper limit is about 60 percent. Flame retardance may be accentuated by adding to the unsaturated polyester containing the hexahalocyclo pentadicne component, a cross-linking agent which al-.o contains the flame retardant properties obtained from a hexahalocyclopentadiene in chemical combination therewith. It may be further accentuated by esterilying a polycarboxylic acid and polyhydric alcohol which each contain the hexahalocyclopentadiene flame retardant conr ponent of this invention and cross-linking this with a fire resistant cross-linking agent. lviechanical filttllr'llt can be accentuated, for example, by employing diallyl diglycol carbonate as the cross-linking agent with a linear unsaturated polyester resin of this invention and forming glass cloth laminates one-eighth inch in thickness. The fiexural strength at room temperature of such a laminated resin is as high as 85,000 pounds per square inch and modulus of elasticity is 4.16%10 pounds Der guare inch.

The properties of the compositions of this invention can be varied substantially by incorporating modifying agents before, during or after any of the processing steps employed. For example, instead of producing articles of commerce from the compositions of this invention which are in the form of castings or laminates as previously described herein, a foamed type article may he made by incorporating a small percentage of a foaming agent such as sodium bicarbonate into the solution of unsaturated polyester dissolved in cross-linking agent and thereafter effecting the copolymerization in the presence of catalyst and heat to produce the foamed article. Formulations which are useful for making moldings embodying the compositions of this invention may be made by mixing into the unsaturated linear polyester and olefinic cross-linking agent mixture a fibrous reinforcing medium and/ or an inert filler such as chopped fiber glass rovings, macerated fabric, asbestos fibers and mica, which serve as fibrous reinforcing media and incorporating a small percentage of a mold lubricant, catalyst and/or promoter.

An infinite variety of products may also be prepared, which embody the copolymers of this invention, by copolymerizing the linear unsaturated polyester materials produced in accordance with this invention, as in Example 1, with a mono-olefinic cross-linking agent in the presence of another copolymerizable linear polyester material having different structure than that produced by this invention. For example, by dissolving 23.1 parts of the product of Example 1 and 4.3 parts of an unchlorinated commercial polyester resin dissolved in styrene and especially designed for imparting flexibility and designated as Paraflex P-13 (made by Rohm and Haas Company, Philadelphia, Pennsylvania) and 2.3 parts by weight of styrene and efiecting the copolymerization of the mixture by a catalyst a material is produced which has better flexibility and difierent properties than any material produced heretofore. It is to be understood that dyes, pigments, plasticizers, lubricants and various other agents are contemplated as being incorporated in certain formulations to produce compositions embraced in this invention in order to obtain or accentuate any given property.

We claim:

1. A polymerizable mixture comprising (A) a polymerizable linear polyester of ingredients comprising (1) a polyhydric alcohol containing aliphatic carbon to carbon unsaturation, and (2) an adduct of hexahalocyclopentadiene and a polycarboxylic compound selected from the group consisting of polycarboxylic acids, acid anhydrides, acid halides and acid esters containing aliphatic carbon to carbon unsaturation wherein the halogen is selected from the group consisting of chlorine, bromine, fluorine and mixtures thereof, and (B) a polymerizable monomer containing a CH =C=group.

2. A composition of claim 1 wherein the said (1) polyhydric alcohol is dihydric and contains ethylenic unsaturation, said adduct (2) is of hexachlorocyclopentadiene and of a dicarboxylic compound containing ethylenic unsaturation, and said (B) polymerizable monomer contains ethylenic unsaturation.

3. A composition of claim 1 wherein said polyhydric alcohol is butynediol.

4. A composition of claim 1 having a polymerization inhibitor added thereto.

5. A composition of claim 1 when polymerized to an infusible, insoluble, resinous composition.

6. A composition of claim 1 when mixed with an inert filler and polymerized to an infusible, insoluble, resinous composition.

7. A reinforced plastic article comprising a composition of claim 1 when polymerized to an infusible, insoluble, resinous composition, and a fibrous reinforcing medi- 8. A laminated article comprising a plurality of sheets of glass fibrous material and as a binder therefor, an infusible, insoluble, resinous composition resulting from the polymerization of a composition defined in claim 1.

9. A composition of claim 2 wherein the adduct is 1,4,5,6,7,7 hexachlorobicyclo (2.2.1) 5 heptene 2,3- dicarboxylic acid.

10. A composition of claim 2 wherein the adduct' is 1,4,5,6,7,7 hexachlorobicyclo (2.2.1) 5 heptene 2,3- dicarboxylic anhydride.

11. A composition of claim 2 wherein said polyhydric alcohol is butenediol.

12. A composition of claim 2 wherein said polyhydric alcohol is alpha allyl glycerol ether.

13. A composition of matter comprising: a polymerizable linear polyester of ingredients comprising a polyhydric alcohol containing aliphatic carbon to carbon unsaturation, and an adduct of hexahalocyclopentadiene and a polycarboxylic compound selected from the group consisting of polycarboxylic acids, acid anhydrides, acid halides and acid esters containing aliphatic carbon to carbon unsaturation wherein the halogen is selected from the group consisting of chlorine, bromine, fluorine and mixtures thereof.

14. A composition of claim 13 wherein said polyhydric alcohol is dihydric and contains ethylenic unsaturation and wherein said adduct is of hexachlorocyclopentadiene and of a dicarboxylic compound containing ethylenic unsaturation.

15. A composition of claim 13 wherein said polyhydric alcohol is butynediol.

16. A composition of claim 14 wherein the adduct is 1,4,5,6,7 ,7 hexachlorobicyclo (2.2.1) 5 heptene 2,3- dicarboxylic acid.

17. A composition of claim 14 wherein the adduct is 1,4,5,6,7,7 hexachlorobicyclo (2.2.1) 5 heptene- 2,3- dicarboxylic anhydride.

18. A composition of claim 14 wherein said polyhydric alcohol is butenediol.

19. A composition of claim 14 wherein said polyhydric alcohol is alpha allyl glycerol ether.

References Cited in the file of this patent UNITED STATES PATENTS 2,606,910 Herzfeld et a1 Aug. 12, 1952 

1. A POLYMERIZABLE MIXTURE COMPRISING (A) A POLYMERIZABLE LINEAR POLYESTER OF INGREDIENTS COMPRISING (1) A POLYHYDRIC ALCOHOL CONTAINING ALIPHATIC CARBON TO CARBON UNSATURATION, AND (2) AN ADDUCT OF HEXAHALOCYCLOPENTADIENE AND A POLYCARBOXYLIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF POLYCARBOXYLIC ACIDS, ACID ANHYDRIDES, ACID HALIDES AND ACID ESTERS CONTAINING ALIPHATIC CARBON TO CARBON UNSATURATION WHEREIN THE HALOGEN IS SELECTED FROM THE GROUP CONSISTING OF CHLORINE, BROMINE, FLUORINE AND MIXTURES THEREOF, AND (B) A POLYMERIZABLE MONOMER CONTAINING A CH2=C=GROUP.
 8. A LAMINATED ARTICLE COMPRISING A PLURALITY OF SHEETS OF GLASS FIBROUS MATERIAL AND AS A BINDER THEREFOR, AND INFUSIBLE, INSOLUBLE, RESINOUS COMPOSITION RESULTING FROM THE POLYMERIZATION OF A COMPOSITION DEFINED IN CLAIM
 1. 